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Experimental Correlation between Mechanical Non‐Linearity in LAOS Flow and Capillary Flow Instabilities for Linear and Branched Commercial Polyethylenes
Author(s) -
Filipe Susana,
Vittorias Iakovos,
Wilhelm Manfred
Publication year - 2008
Publication title -
macromolecular materials and engineering
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.913
H-Index - 96
eISSN - 1439-2054
pISSN - 1438-7492
DOI - 10.1002/mame.200700194
Subject(s) - die swell , rheometry , materials science , polyethylene , extrusion , linearity , linear low density polyethylene , flow (mathematics) , capillary action , composite material , rheology , thermodynamics , mechanics , physics , quantum mechanics
An experimental correlation between the non‐linear behaviour of commercial polyethylene melts in LAOS flow, and the pressure fluctuations associated with melt flow instabilities developed in capillary rheometry are presented. Polyethylene melts with enhanced non‐linear behaviour under LAOS conditions present larger pressure fluctuations during capillary extrusion, and consequently, larger surface distortions on the extrudate. The combination of both methods can be a tool to predict the development of melt flow instabilities in the extrusion process of polyethylene melts, and can elucidate their correlation with material structural properties ( $\overline M _{\rm w}$ , MWD and topology).